Effect of horizon roughness on lateral continuity and amplitude variation of deeper reflections
Effect of horizon roughness on lateral continuity and amplitude variation of deeper reflections
The aim of this study is to investigate the fractal properties of natural rough topographies and to study seismic wave scattering from them, in particular their effects on the deeper reflection continuity and amplitude variation. The distortions caused by shallow rough horizons to the deeper reflections are very significant if the rough horizons are associated with high acoustic impedance contrast. This problem has been experienced in many petroleum provinces such as to the west of Ireland and in the Faeroe-Shetland basin, where thick Tertiary basalt flows are present above the sedimentary sequences of interest. Seismic reflection data from the Faeroe-Shetland basin clearly shows the sub-basalt target horizons to be highly discontinuous and low frequency, which make accurate structural or stratigraphic interpretations very difficult. In this work a forward modelling approach is followed where Depth-Velocity (DV) models with rough interfaces are prepared and input to Finite-Difference (FD) modelling to produce synthetic seismic sections which are then compared to the original seismic reflection data.
There are two major aspects of the work: firstly to understand the reflection characteristics from large as well as small scale structures present on geological interfaces; and secondly to obtain the roughness of the real sub-surface horizons present in the area for incorporation in realistic DV models, so that their net scattering effects on deeper reflections can be ascertained. Initially simple models comprising a sinusoidal interface with different heights and spatial wavelengths were prepared and the focusing/defocusing effects on the underlying constant reflection coefficient plane horizons were studied. Geometric expressions were derived to demonstrate that the fresnel zone width is larger over the synclines than the anticlines so that the amplitude effects on underlying reflectors can be quantified.
University of Southampton
Walia, Rakesh Kumar
af1fb501-8d45-4073-9496-ce7c22c612e5
1997
Walia, Rakesh Kumar
af1fb501-8d45-4073-9496-ce7c22c612e5
Walia, Rakesh Kumar
(1997)
Effect of horizon roughness on lateral continuity and amplitude variation of deeper reflections.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The aim of this study is to investigate the fractal properties of natural rough topographies and to study seismic wave scattering from them, in particular their effects on the deeper reflection continuity and amplitude variation. The distortions caused by shallow rough horizons to the deeper reflections are very significant if the rough horizons are associated with high acoustic impedance contrast. This problem has been experienced in many petroleum provinces such as to the west of Ireland and in the Faeroe-Shetland basin, where thick Tertiary basalt flows are present above the sedimentary sequences of interest. Seismic reflection data from the Faeroe-Shetland basin clearly shows the sub-basalt target horizons to be highly discontinuous and low frequency, which make accurate structural or stratigraphic interpretations very difficult. In this work a forward modelling approach is followed where Depth-Velocity (DV) models with rough interfaces are prepared and input to Finite-Difference (FD) modelling to produce synthetic seismic sections which are then compared to the original seismic reflection data.
There are two major aspects of the work: firstly to understand the reflection characteristics from large as well as small scale structures present on geological interfaces; and secondly to obtain the roughness of the real sub-surface horizons present in the area for incorporation in realistic DV models, so that their net scattering effects on deeper reflections can be ascertained. Initially simple models comprising a sinusoidal interface with different heights and spatial wavelengths were prepared and the focusing/defocusing effects on the underlying constant reflection coefficient plane horizons were studied. Geometric expressions were derived to demonstrate that the fresnel zone width is larger over the synclines than the anticlines so that the amplitude effects on underlying reflectors can be quantified.
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Published date: 1997
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Local EPrints ID: 460189
URI: http://eprints.soton.ac.uk/id/eprint/460189
PURE UUID: 89f3f9a0-03bf-48fa-95a4-a8077f62aaa7
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Date deposited: 04 Jul 2022 18:09
Last modified: 16 Mar 2024 18:36
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Author:
Rakesh Kumar Walia
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